12 Memoirs of the Indian Museum. [Vol. I, 



and broad, though head is long ; no long piles or bristles ; molars tritubercular. A 

 house and drain rat ; does not spit or bristle when caged. — Mus decumanus : the 

 Brown Rat. 



3. Heavy -bodied, of moderate size, like a small M. decumanus, but has long 

 piles or bristles on back ; tail tapers suddenly and is about 70 cent, of the length of 

 the head and body ; uniformly black and nearly naked ; pads of hind foot small and 

 nearly circular, not cordiform, proximo-external pad very small, and in 2 per cent, of 

 specimens wanting ; feet and nose light purplish, not flesh-coloured, proportionately 

 small ; fur thin and bristly, giving drowned specimens a half-naked appearance ; 

 molars with transverse laminae. Burrowing, grainstoring, stable, and grainshop rat ; 

 erects its bristles and spits when caged. — Nesokia bengalensis : the Indian Mole Rat. 



4. Extremely large and heavy-bodied ; muzzle greyhound-like compared with 

 decumanus, deep and narrow ; tail almost equal in length to head and body ; ears 

 long ; very long black piles 5 to 6 cm. in length ; feet extremely large, atreous, with 

 six round pads as in N . bengalensis, tail generally black and more naked than in large 

 s^çiQ.\mQ.ns oi decumanus ; burrowing, grainstoring, frequenting gardens but is cap- 

 tured in houses ; molars with transverse laminae. Erects its bristles and spits when 

 caged. — Nesokia handicota var. nemorivagus : the Lesser Bandicoot. 



SPECIES OF RATS IN CALCUTTA AND THEIR RELATIVE FREQUENCY. 



Four species of rats were found, the first two equally common and predominant, 

 the third not so common, and the fourth very rare : — 



1 . Mus decumanus, 26 % . 



2. Nesokia bengalensis, 60%. 



3. Mus rattus, 14%. 



4. Nesokia bandicota var. nemorivagus , rare. 



The figures of relative frequency tend to be rather unsatisfactory from various 

 causes. In the first place pressure of plague work made it impossible for me to make 

 accurate recorded counts of any but a small proportion of the rats I examined. In 

 the second place it was only late in my investigation that I could accurately distin- 

 guish the different varieties. In the third place experience has shown me that the 

 proportions vary in different parts of the city ; in the north, where grain-stores and 

 huts abound, N. bengalensis is the common rat, accounting for 50% to 60% of 

 the total ; while in the central and European parts Mus decumanus is almost equally 

 predominant. The Bandicoot is found mainly in gardens in the suburbs on the banks 

 of tanks, but it is comparatively very rare. My colleague Dr. Crake, counted 1,000 

 rats but only distinguished long- tailed rats, i.e., Mus rattus, from all other species, 

 making the former 11 2 per cent, of the total. 



Later figures based on the rats collected at the Head Office from August to Decem- 

 ber 1906, show strikingly the difference between the rat populations of the northern 

 native city to which the first count refers and the central European portion in the 

 heart of which the Head Office is situated. The figures are as follows- — 



